Plastic biodegradable reclosable zipper for flexible packages

ABSTRACT

A fastener for a reclosable container is constructed of a biodegradable material. The fastener includes two tracks that interlock to close the container. The fastener may include flanges to prevent damage to other portions of the container. The material may contain a small percentage of starch to permit the fastener to biodegrade within a few years after the container has been discarded. The remainder of the container may also be constructed of a biodegradable material.

TECHNICAL FIELD

The present invention relates to biodegradable and degradable containers and in particular to reclosable fasteners to seal containers made from these materials.

BACKGROUND OF THE INVENTION

Containers such as so called plastic bags have long been a source of non-degradable materials found in landfills and littered in the environment. Biodegradable materials have been developed for the plastics, usually polyethylene and polypropylene, to allow the bags to breakdown. The film for these bags may be cast or blown during production. Typically, a biodegradable material will breakdown in a manner of years or months, depending upon the constituents of the material.

Reclosable containers such as bags have been developed to generally permit a user to open and reseal the container. Typically, these reclosable containers incorporate a fastener adjacent a container end to releasably affix opposing walls of the container, thereby selectively forming a bag opening defined by the releasable fastener. For containers where an seal is desired, the fastener may include a pair of longitudinal tracks that bindingly engage where each track is secured to a wall of the container. Differing profiles for the longitudinal tracks may be selected based upon factors such as force required to open/close,

One disadvantage of known biodegradable containers in the form of bag-like structures is that the entire container is actually not biodegradable. In particular, a biodegradable reclosable fastener has not been in use. What is needed, therefore, is a fastener for a container that is bag-like, which is biodegradable, easily manufactured, and readily adhered to at least a part of the container.

SUMMARY OF THE INVENTION

An embodiment of the present invention provides a biodegradable fastener for a container, the fastener including a first track and a second track. The first track has a first base and a joining surface extending therefrom. The second track has a second base and an engaging surface extending therefrom. The joining surface and the engaging surface matingly engage to releasably fasten the first base to the second base.

Another embodiment of the present invention provides a container that includes a film enclosure wall and a fastener. The fastener is coupled to at least part of the wall. The fastener selectively encloses at least a portion of the container. At least a portion of the fastener is biodegradable.

Yet another embodiment of the present invention provides a method of manufacturing a fastener. The method includes forming a first track having a first base and a joining surface extending therefrom and forming a second track having a second base and a complementary engaging surface extending therefrom. The joining surface and the engaging surface matingly engage to releasably fasten the first base to the second base. At least one of the first track and the second track is biodegradable.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a container in accordance with an embodiment of the present invention.

FIG. 2 is a partial sectional view of the container of FIG. 1, taken along line 2-2 of FIG. 1.

FIG. 3 is a partial sectional view of the container of FIG. 1, taken along line 3-3 of FIG. 1, illustrating a fastener with the remainder of the container removed for clarity.

FIG. 4 is a sectional view of an alternative embodiment of a fastener in accordance with the present invention.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, an embodiment of a container 20 is illustrated. Container 20 includes a first wall 22 and a second wall 24. The first wall 22 and the second wall 24 are connected by a first seam 26, a second seam 28, a third seam 30, and a releasable fastener 40, possibly in the form of a zipper. First wall 22 includes a first end 32 and second wall 24 includes a second end 34.

Any one of seams 26, 28, 30 may be a fold of a continuous material of walls 22, 24 and not a joining of the materials of walls 22, 24. Container 20 is preferably sealed generally air-tight by seams 26, 28, 30 and fastener 40, as described in greater detail herein, although container 20 need not be an air tight container. As best seen in FIG. 1, fastener 40 includes a first end 42 and a second end 44. In two of the possible embodiments fastener 40 is affixed to at least a part of walls 22, 24 by heat fusing or adhesive.

As best seen in FIG. 3, a disclosed fastener 40 includes a first track 50 and a second track 52. The first track 50 includes a first base 54 with a first pair of interlocking ribs 58 extending therefrom. The second track 52 includes a second base 60 with a second pair of interlocking ribs 62 extending therefrom. Interlocking ribs 58 are defined, at least in part, by a joining surface 66. Interlocking ribs 62 are defined, at least in part, by an engaging surface 68. At least portions of joining surface 66 and engaging surface 68 are in contact as fastener 40 is in a closed position, as illustrated in FIGS. 1-3.

Fastener 40 has a width W, measured in a transverse direction, a length L (FIG. 1), measured in a longitudinal direction, and a height T, measured generally perpendicular to the transverse and longitudinal directions. At least a portion of joining surface 66 is defined by a generally transversely extending first planar surface 76. At least a portion of engaging surface 68 is defined by a generally transversely extending second planar surface 78.

To open container 20, a user may grasp first end 32 and separately grasp second end 34. The user then may pull first end 32 away from second end 34, thereby separating at least a portion of the first track 50 from the second track 52. The first track 50 and the second track 52 of fastener 40 may not be separated at first end 42 and second end 44. Therefore, fastener 40 provides access to the inside of container 20.

To close container 20, a user may grasp fastener 40 at first end 42 and squeeze together tracks 50, 52 along the length L of fastener 40 to interlock tracks 50, 52 as illustrated in FIG. 3.

FIG. 4 illustrates an alternative embodiment of the container 20 as a container 120. Container 120 includes a first wall 122 having a first end 132, a second wall 124 having a second end 134, and a fastener 140.

Fastener 140 includes a first track 150 and a second track 152. The first track 150 includes a first base 154 with a first flange 156 and a first pair of interlocking ribs 158 extending therefrom. The second track 152 includes a second base 160 with a second pair of interlocking ribs 162 and a second flange 164 extending therefrom. Interlocking ribs 158 are defined, at least in part, by a joining surface 166. Interlocking ribs 162 are defined, at least in part, by an engaging surface 168. At least portions of joining surface 166 and engaging surface 168 are in contact as fastener 140 is in a closed position.

Fastener 140 has a width W1, measured in a transverse direction, a length L1 (not shown), measured in a longitudinal direction, and a height T1, measured generally perpendicular to the transverse and longitudinal directions. At least a portion of joining surface 166 is defined by a generally transversely extending first planar surface 176. At least a portion of engaging surface 168 is defined by a generally transversely extending second planar surface 178.

To open container 120, a user may grasp first end 132 and flange 156 and separately grasp second end 134 and flange 164. The user then may pull flange 156 away from flange 164, thereby separating at least a portion of the first track 150 from the second track 152. Therefore, flanges 156, 164 provide a portion of fastener 140 to grasp when opening container 120 and may prevent tracks 150, 152 from separating from walls 122, 124 when the user pulls to open container 120. Container 120 is closed in a similar manner as container 20.

Walls 22, 24, 122, 124 preferably have a thickness of about 1 mil, although any appropriate thickness may be used for container 20, 120, including a range of about 0.1 mil to about 500 mil. As discussed below, containers 20, 120 and fasteners 40, 140 may be formed of any desired dimensions from a resiliently deformable, biodegradable polymer blend. Since walls 22, 24, 122, 124 are typically cast or blown and fasteners 40, 140 are desirably extruded, the differing forming techniques generally dictate differing desired material characteristics.

Preferably, the material for fasteners 40, 140 is a degradable polymer. More preferably, fasteners 40, 140 are constructed of a biodegradable blend of starch, or other suitable material, and either a polyethylene or polypropylene. Fasteners 40, 140 may be any weight percent biodegradable material with the remainder being essentially polyethylene or polypropylene. Preferably, fasteners 40, 140 are about 1 to about 5 weight percent starch. While the biodegradable additive to the polymer material for fastener 40, 140 is described as starch based, other materials that provide a desirable degradation may be added to a polymer to produce a suitable material.

While the materials for the biodegradable fasteners 40, 140 and container 20 will desirably degrade in accordance with accepted standards, such as ASTM standards, the disclosure of which is hereby incorporated by reference in its entirety, other materials that favorably degrade and may not meet the requirements of applicable standards are also within the scope of the embodiments of the invention.

In one embodiment of manufacturing the fastener 40, die extrusion is used. Tracks 50, 52 are extruded separately and may be joined and stored on a spool. Fastener 40 is then heat fused (welded) or adhered to walls 22, 24. Seams 26, 28 may be heat fused as ends 42, 44 are simultaneously heat fused. Heat fusing is process to desirably seal seams 26, 28, and ends 42, 44 as they are trimmed. To adequately heat fuse ends 42, 44, pressure is applied as tracks 50, 52 are trimmed to produce ends 42, 44 while fusing tracks 50, 52 at ends 42, 44. Ends 32, 34 are trimmed and seam 30 is heat fused, if not previously folded, to produce the container 20. Container 120 is produced in a similar manner.

While the invention has been described with respect to specific examples including preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims. 

1. A fastener for a container comprising: a first track having a first base and a joining surface extending therefrom; and a second track having a second base and a engaging surface extending therefrom, wherein said joining surface and said engaging surface matingly engage to releasably fasten said first base to said second base, and wherein said first track and said second track are biodegradable.
 2. The fastener of claim 1, wherein said fastener is constructed of a starch and a polymer.
 3. The fastener of claim 2, wherein said polymer is selected from the group consisting of polyethylene and polypropylene.
 4. The fastener of claim 1, wherein said biodegradable track is about 0.001 to about 10 weight percent of said fastener.
 5. The fastener of claim 2, wherein said starch is about 1 to about 5 weight percent of said fastener.
 6. The fastener of claim 2, wherein said starch is blended with said polymer to form a material that may be extruded.
 7. The fastener of claim 1, wherein at least one of said first track and said second track has a rib extending therefrom and said rib extends generally along a transverse direction forming generally a planar surface.
 8. The fastener of claim 1, wherein at least one of said joining surface and said engaging surface includes a transversely extending rib.
 9. The fastener of claim 1, wherein said first track has a generally consistent cross section along a longitudinal length.
 10. A container comprising: a film enclosure wall; and a fastener coupled to said wall, wherein said fastener selectively encloses at least a portion of said container and at least a portion of said fastener is biodegradable.
 11. The container of claim 10, wherein said fastener is welded to said wall.
 12. The container of claim 10, wherein at least a portion of said wall is biodegradable.
 13. The container of claim 10, wherein said fastener selectively seals said container.
 14. The container of claim 10, further comprising a second film enclosure wall.
 15. The container of claim 14, wherein said second film enclosure wall is sealed to said first enclosure wall at least along two edges, and said fastener is welded to said second enclosure wall.
 16. The container of claim 10, wherein said fastener is constructed of a starch and a polymer.
 17. The container of claim 10, wherein said fastener includes: a first track having a first base and a joining surface extending therefrom; and a second track having a second base and a complementary engaging surface extending therefrom, wherein said joining surface and said engaging surface matingly engage to releasably fasten said first base to said second base.
 18. The container of claim 17, wherein said first track has a generally consistent cross section along a longitudinal length.
 19. A method of manufacturing a fastener comprising the steps of: forming a first track having a first base and a joining surface extending therefrom; and forming a second track having a second base and a complementary engaging surface extending therefrom, wherein said joining surface and said engaging surface matingly engage to releasably fasten said first base to said second base, and wherein at least one of said first track and said second track is biodegradable.
 20. The method of claim 19, further comprising blending a starch and a polymer to form a material for said fastener.
 21. The method of claim 19, wherein each of said steps of forming include extrusion. 